This application claims priority from U.S. patent application Ser. No. 61/027,565, filed Feb. 11, 2008, which is hereby incorporated herein by reference. The present invention relates to packing material and methods for protecting articles to be shipped and is a further development of the product described in U.S. Pat. No. 6,085,909 (the '909 patent), which is hereby incorporated herein by reference.
The '909 patent teaches a reusable flexible packing bag that is filled with free-flowing beads, such as expanded polystyrene beads. The air is evacuated from the bag, and then the bag is sealed so that the internal pressure inside the bag is less than the external pressure from the ambient air. The pressure differential is enough to prevent the beads from flowing freely. Instead, they remain closely packed, and the bag maintains its shape. The bag preferably is formed into a flat shape before it is sealed, so the result is a substantially flat packing material that generally keeps its shape but that can be bent to wrap around an article to be packaged in order to conform to the contour of the article or of the package to cushion the article during shipping.
As explained above, the pressure differential between the ambient pressure acting on the outside of the packing bag and the pressure acting on the inside of the bag after it is sealed is sufficient to maintain the beads in a non-free-flowing condition. It is preferred that the pressure differential be at least 0.3 pounds per square inch and more preferable that is be at least 0.5 pounds per square inch. Since the ambient atmospheric pressure is usually 14.7 pounds per square inch, the internal pressure inside the bag preferably is no greater than 14.4 pounds per square inch and more preferably not greater than 14.2 pounds per square inch.
While the packing materials described in the '909 patent are readily used to wrap around a product or to fit along the inside of a box to protect against damage during shipping, the proper placement of the packing material depends upon the skill and judgment of the person who is placing it and therefore may not be consistently reproduced. Also, it takes time to properly position the packing.